The apparatus according to the invention is described in more detail below, purely by way of example, with reference to a specific working example shown schematically in the drawings. Specifically:
FIG. 1 shows a vacuum valve drive in the opened position in a cross-sectional side view;
FIG. 2 shows the vacuum valve drive in the closed position in the cross-sectional side view;
FIG. 3 shows a detailed view of a precision linear roller bearing having a guide sleeve and a sleeve-like separator;
FIG. 4 shows a plan view of the piston; and
FIG. 5 shows an oblique view of a vacuum valve comprising a valve housing, a valve closure and the vacuum valve drive in the closed position.
Below, FIGS. 1 to 5 are described in some cases together, reference numerals already explained beforehand in individual Figures not being discussed again separately. FIG. 1 shows a possible embodiment of a vacuum valve drive 1 according to the invention in a lateral cross-sectional view, the vacuum valve drive 1 being in the completely opened position A in which a valve closure 2 (cf. FIG. 5) mounted on the vacuum valve drive 1 is completely opened. FIG. 2 shows the same vacuum valve drive 1 in the closed position B. The vacuum valve drive 1 shown comprises a multipart drive housing 5 which contains a substantially gas-tight working space 6. The working space 6 has a slot-like cross-section in plan view in the direction of the adjustment axis 3. A piston 7 which is displaceable along the adjustment axis 3 is arranged inside the working space 6 in such a way that the piston 7 divides the working space 6 into a first pressure space 6a present on the connection side 30 and a second pressure space 6b arranged on the valve side 29. The pressure spaces 6a and 6b are separated substantially gas-tight by the piston 7. For this purpose, the piston 7 and the working space 6 have a cross-section corresponding to one another, the lateral all-round gap between the outer surface 16 of the piston and the inner surface 17 of the working space 6 being closed gas-tight by means of two piston packings 26 surrounding the piston 7. The piston 7 and the working space 6 have an elongated, in this case slot-like, alternatively oval, cross-section, the cross-sectional length X being more than twice, in the present case more than five times, the cross-sectional width Y, as shown in the plan view of the piston 7 in FIG. 4. This makes it possible to make the drive housing extremely flat so that a space-saving arrangement of the vacuum valve is possible.
Two connecting rods 8 and 9 which extend parallel to the adjustment axis 3 and are led to the valve side 29 from the second pressure space 6b of the working space 6 in a gas-tight manner by means of one connecting rod seal 28a and 28b each into the outer region of the drive housing 5 are fixed to the piston 7. In each case a mounting peg 23a and 23b on which the valve closure 2 can be mounted is present at the end of the connecting rods 8 and 9. For a gas-tight seal between the valve housing 20 (cf. FIG. 5) and the ambient atmosphere, a bellows lead-through 24a and 24b, respectively, is provided for each connecting rod 8 and 9, as known from the prior art.
The piston 7 is guided linearly along the adjustment axis 3 via a static guide rod 11 extending parallel to the adjustment axis 3 and centrally inside the working space 6 and connected to the drive housing 5. The guide rod 11 has a round cross-section but may also have any other desired suitable cross-section. The two connecting rods 8 and 9 extending parallel to the adjustment axis 3 are fixed to the piston 7, opposite the central guide rod 11, as also shown in plan view in FIG. 4. Thus, the two connecting rods 8 and 9, the guide rod 11 and the adjustment axis 3 are parallel to one another, the guide rod 11 extending in the middle between the connecting rods 8 and 9. The central guide rod 11 is led in a substantially gas-tight manner through the piston 7, a guide rod seal 27 in the form of an O-ring arranged on the piston 7 substantially preventing gas exchange between the first and the second pressure spaces 6a and 6b.
A precision linear roller bearing 12 for highly precise linear guidance of the piston 7 and hence also of the connecting rods 8 and 9 and of the valve closure 2 mounted thereon is arranged between the piston 7 and the guide rod 11. This precision linear roller bearing 12 is shown in more detail in FIG. 3 and is composed of a guide sleeve 13, which is fixed to the piston 7, in particular by means of adhesive bonding, and surrounds the guide rod 11, and a sleeve-like separator 14. The separator 14 holds roll bodies 15 between the guide rod 11 and the guide sleeve 13 in such a way that the guide sleeve 13 is mounted radially without play on the guide rod 11 so as to be linearly displaceable along the adjustment axis 3. The roll bodies are formed by a multiplicity of balls 15 distributed in a plurality of rows around the guide rod 11 and parallel to the adjustment axis 3. Such precision linear roller bearings 12 are generally known from the prior art. The separator 14 executes a stroke of the piston 7 and of the guide sleeve 13 approximately at half speed and thus moves only half way between the positions A and B, as is clearly evident from the respective position of the separator 14 relative to the guide sleeve 13 in FIGS. 1 and 2. A piston guide band 18 resting on the adjacent inner surface 17 of the working space 6 and running parallel to the piston packings 26 is arranged on the outer surface 16 of the piston in such a way that the piston 7 is prevented from rotating about the guide rod axis. The piston 7 is linearly guided with high precision and centred in the working space 6 by the guide rod 11 so that the valve closure 2 coupled thereto is moved with high precision and pressed onto the valve seat 22 (cf. FIG. 5), any particle generation by undesired friction being avoided.
In an alternative embodiment, a precision linear sliding bearing is used instead of the precision linear roller bearing 12. In this case, the separator 14 and the roll bodies 15 are omitted. The distance between the guide rod 11 and the guide sleeve 13 should be chosen to be so small that the guide sleeve 13, which is arranged on the piston 7, surrounds the guide rod 11 substantially radially without play in the manner of a sliding bearing, so that play-free linear mounting is achieved.
A first connection 10a on the drive housing 5, which leads into the first pressure space 6a, makes it possible to apply gas pressure to the first pressure space 6a, as shown by the arrow in FIG. 1. For application of pressure to the second pressure space 6b, a second connection 10b leading into the second pressure space 6b (cf. arrow in FIG. 2) is provided adjacent on the same connection side 30 on the drive housing 5 so that the valve closure 2 arranged on the connecting rods 8 and 9 can be moved between the opened position A and the closed position B by producing a gas pressure difference between the first pressure space 6a and the second pressure space 6b. The connection between the second connection 10b and the second pressure space 6b is permitted by a channel 19 which opens into the second pressure space 6b and is formed inside the guide rod 11 in the form of a longitudinal bore. The flow path through the channel 9 is illustrated in FIG. 2 by means of the arrow.
In the second pressure space 6b arranged on the valve side 29 of the drive housing 5, a damping bore 31 is formed in the drive housing 5. A partial section of the guide rod 11 is led centrally and radially a distance away through the damping bore 31 so that a sleeve-like space closed towards the valve side 29 and open towards the piston side is formed. A damping bore seal 32 in the form of an O-ring is present in the damping bore 31, on the inner edge section on the piston side. An additional channel 33 which leads from the damping bore 31 into the second pressure space 6b and forms a flow path bypassing the damping bore seal 32 is also provided in the drive housing 5. The channel 19 formed inside the guide rod 11 opens into that partial section of the guide rod 11 which is surrounded by the damping bore 31. The guide sleeve 13, the separator 14, the damping bore 31 and the damping bore seal 32 are dimensioned and arranged in such a way that, on going over from the opened position A into the closed position B (cf. FIG. 2), the guide sleeve 13 is introduced into the damping bore 31 and a substantially radially sealing contact is produced between the damping bore seal 32 and the guide sleeve 13. Thus, an excess pressure builds up briefly in the damping bore 31 during the closing process, with the result that the closing valve closure 2 is braked before reaching the closed position B, owing to the gas displacement via the additional channel 33. The arrangement described thus provides pneumatic damping on going over into the closed position B, so that damage to the valve closure 2 and undesired particle generation can be avoided even on fast valve actuation. By means of the guide rod 11, the piston 7 is thus guided linearly, centred in the working space 6 and damped in combination with the damping bore 31 shortly before reaching the closed position B. Moreover, the gas feed into the second pressure space 6b is facilitated since both connections 10a and 10b can be arranged on a common connection side 30 on the drive housing 5.
FIG. 5 shows a vacuum valve 4 for substantially gas-tight closing of a flow path F, comprising a valve housing 20 having an opening 21 for the flow path F and a valve seat 22, and comprising the vacuum valve drive 1 already described above, the vacuum valve 4 being in the closed position B. The valve closure 2 is linearly displaceable along the adjustment axis 3 (cf. FIGS. 1 and 2), between an opened position A unblocking the opening 21 and a position B in which the vacuum valve 4 is closed gas-tight and the valve closure is linearly displaced over the opening 21 and hence pressed onto the valve seat 22, as shown in FIG. 5. The vacuum valve drive 1 already described serves for the linear displacement of the valve closure 2 along the adjustment axis 3 between the opened position A and the position B with gas-tight closure. By means of the bellows lead-throughs 24a and 24b, the connecting rods 8 and 9 are introduced in a gas-tight manner into the valve housing 20 and connected to the valve closure 2 inside the valve housing 20. FIG. 5 illustrates the flat design of the vacuum valve 4, in particular of the vacuum valve drive 1 in the direction of the flow path F, permitted by the vacuum valve drive 1 according to the invention. Thus, a space-saving and flexible arrangement of the vacuum valve is possible.
FIGS. 1 and 5 show a possible embodiment of the invention. Of course, the invention is not limited to this embodiment. Alternative designs of the vacuum valve and of the vacuum valve drive are possible within the scope of the invention.
Patent Application
20070257220
